Multi-channel audio signals are used to store or transport a listening experience, for an end listener, that may include the impression of a very complex acoustic scene. The multi-channel signals may carry the information that describes the acoustic scene using a number of common conventions including, but not limited to, the following:
Discrete Speaker Channels: The audio scene may have been rendered in some way, to form speaker channels which, when played back on the appropriate arrangement of loudspeakers, create the illusion of the desired acoustic scene. Examples of Discrete Speaker Channel Formats include stereo, 5.1 or 7.1 signals, as used in many sound formats today.
Audio Objects: The audio scene may be represented as one or more object audio channels which, when rendered by the listeners playback equipment, can re-create the acoustic scene. In some cases, each audio object will be accompanied by metadata (implicit or explicit) that is used by the renderer to pan the object to the appropriate location in the listeners playback environment. Examples of Audio Object Formats include Dolby Atmos, which is used in the carriage of rich sound-tracks on Blu-Ray Disc and other motion picture delivery formats.
Soundfield Channels: The audio scene may be represented by a Soundfield Format—a set of two of more audio signals that collectively contain one or more audio objects with the spatial location of each object encoded in the Spatial Format in the form of panning gains. Examples of Soundfield Formats include Ambisonics and Higher Order Ambisonics (both of which are well known in the art).
This disclosure is concerned with the modification of multi-channel audio signals that adhere to various Spatial Formats.